﻿/*
 * FCKeditor - The text editor for Internet - http://www.fckeditor.net
 * Copyright (C) 2003-2009 Frederico Caldeira Knabben
 *
 * == BEGIN LICENSE ==
 *
 * Licensed under the terms of any of the following licenses at your
 * choice:
 *
 *  - GNU General Public License Version 2 or later (the "GPL")
 *    http://www.gnu.org/licenses/gpl.html
 *
 *  - GNU Lesser General Public License Version 2.1 or later (the "LGPL")
 *    http://www.gnu.org/licenses/lgpl.html
 *
 *  - Mozilla Public License Version 1.1 or later (the "MPL")
 *    http://www.mozilla.org/MPL/MPL-1.1.html
 *
 * == END LICENSE ==
 */

var FCKUndo = new Object() ;

FCKUndo.SavedData = new Array() ;
FCKUndo.CurrentIndex = -1 ;
FCKUndo.TypesCount = 0 ;
FCKUndo.Changed = false ;    // Is the document changed in respect to its initial image?
FCKUndo.MaxTypes = 25 ;
FCKUndo.Typing = false ;
FCKUndo.SaveLocked = false ;

FCKUndo._GetBookmark = function()
{
    FCKSelection.Restore() ;

    var range = new FCKDomRange( FCK.EditorWindow ) ;
    try
    {
        // There are some tricky cases where this might fail (e.g. having a lone empty table in IE)
        range.MoveToSelection() ;
    }
    catch ( e )
    {
        return null ;
    }
    if ( FCKBrowserInfo.IsIE )
    {
        var bookmark = range.CreateBookmark() ;
        var dirtyHtml = FCK.EditorDocument.body.innerHTML ;
        range.MoveToBookmark( bookmark ) ;
        return [ bookmark, dirtyHtml ] ;
    }
    return range.CreateBookmark2() ;
}

FCKUndo._SelectBookmark = function( bookmark )
{
    if ( ! bookmark )
        return ;

    var range = new FCKDomRange( FCK.EditorWindow ) ;
    if ( bookmark instanceof Object )
    {
        if ( FCKBrowserInfo.IsIE )
            range.MoveToBookmark( bookmark[0] ) ;
        else
            range.MoveToBookmark2( bookmark ) ;
        try
        {
            // this does not always succeed, there are still some tricky cases where it fails
            // e.g. add a special character at end of document, undo, redo -> error
            range.Select() ;
        }
        catch ( e )
        {
            // if select restore fails, put the caret at the end of the document
            range.MoveToPosition( FCK.EditorDocument.body, 4 ) ;
            range.Select() ;
        }
    }
}

FCKUndo._CompareCursors = function( cursor1, cursor2 )
{
    for ( var i = 0 ; i < Math.min( cursor1.length, cursor2.length ) ; i++ )
    {
        if ( cursor1[i] < cursor2[i] )
            return -1;
        else if (cursor1[i] > cursor2[i] )
            return 1;
    }
    if ( cursor1.length < cursor2.length )
        return -1;
    else if (cursor1.length > cursor2.length )
        return 1;
    return 0;
}

FCKUndo._CheckIsBookmarksEqual = function( bookmark1, bookmark2 )
{
    if ( ! ( bookmark1 && bookmark2 ) )
        return false ;
    if ( FCKBrowserInfo.IsIE )
    {
        var startOffset1 = bookmark1[1].search( bookmark1[0].StartId ) ;
        var startOffset2 = bookmark2[1].search( bookmark2[0].StartId ) ;
        var endOffset1 = bookmark1[1].search( bookmark1[0].EndId ) ;
        var endOffset2 = bookmark2[1].search( bookmark2[0].EndId ) ;
        return startOffset1 == startOffset2 && endOffset1 == endOffset2 ;
    }
    else
    {
        return this._CompareCursors( bookmark1.Start, bookmark2.Start ) == 0
            && this._CompareCursors( bookmark1.End, bookmark2.End ) == 0 ;
    }
}

FCKUndo.SaveUndoStep = function()
{
    if ( FCK.EditMode != FCK_EDITMODE_WYSIWYG || this.SaveLocked )
        return ;

    // Assume the editor content is changed when SaveUndoStep() is called after the first time.
    // This also enables the undo button in toolbar.
    if ( this.SavedData.length )
        this.Changed = true ;

    // Get the HTML content.
    var sHtml = FCK.EditorDocument.body.innerHTML ;
    var bookmark = this._GetBookmark() ;

    // Shrink the array to the current level.
    this.SavedData = this.SavedData.slice( 0, this.CurrentIndex + 1 ) ;

    // Cancel operation if the new step is identical to the previous one.
    if ( this.CurrentIndex > 0
            && sHtml == this.SavedData[ this.CurrentIndex ][0]
            && this._CheckIsBookmarksEqual( bookmark, this.SavedData[ this.CurrentIndex ][1] ) )
        return ;
    // Save the selection and caret position in the first undo level for the first change.
    else if ( this.CurrentIndex == 0 && this.SavedData.length && sHtml == this.SavedData[0][0] )
    {
        this.SavedData[0][1] = bookmark ;
        return ;
    }

    // If we reach the Maximum number of undo levels, we must remove the first
    // entry of the list shifting all elements.
    if ( this.CurrentIndex + 1 >= FCKConfig.MaxUndoLevels )
        this.SavedData.shift() ;
    else
        this.CurrentIndex++ ;

    // Save the new level in front of the actual position.
    this.SavedData[ this.CurrentIndex ] = [ sHtml, bookmark ] ;

    FCK.Events.FireEvent( "OnSelectionChange" ) ;
}

FCKUndo.CheckUndoState = function()
{
    return ( this.Changed || this.CurrentIndex > 0 ) ;
}

FCKUndo.CheckRedoState = function()
{
    return ( this.CurrentIndex < ( this.SavedData.length - 1 ) ) ;
}

FCKUndo.Undo = function()
{
    if ( this.CheckUndoState() )
    {
        // If it is the first step.
        if ( this.CurrentIndex == ( this.SavedData.length - 1 ) )
        {
            // Save the actual state for a possible "Redo" call.
            this.SaveUndoStep() ;
        }

        // Go a step back.
        this._ApplyUndoLevel( --this.CurrentIndex ) ;

        FCK.Events.FireEvent( "OnSelectionChange" ) ;
    }
}

FCKUndo.Redo = function()
{
    if ( this.CheckRedoState() )
    {
        // Go a step forward.
        this._ApplyUndoLevel( ++this.CurrentIndex ) ;

        FCK.Events.FireEvent( "OnSelectionChange" ) ;
    }
}

FCKUndo._ApplyUndoLevel = function( level )
{
    var oData = this.SavedData[ level ] ;

    if ( !oData )
        return ;

    // Update the editor contents with that step data.
    if ( FCKBrowserInfo.IsIE )
    {
        if ( oData[1] && oData[1][1] )
            FCK.SetInnerHtml( oData[1][1] ) ;
        else
            FCK.SetInnerHtml( oData[0] ) ;
    }
    else
        FCK.EditorDocument.body.innerHTML = oData[0] ;

    // Restore the selection
    this._SelectBookmark( oData[1] ) ;

    this.TypesCount = 0 ;
    this.Changed = false ;
    this.Typing = false ;
}
